Calculate angles between two intersecting lines using the slopes if one slope is infinite

For example m1=√3/2 & m2 = infinity

Answer 1

[Star Strider]

An infinite slope is a vertical line, so this is straightforward:

m1 = sqrt(3/2);
thr = pi/2 - atan2(m1, 1);
thd = thr * 180/pi;

figure(1)
plot([0 0], [0 1.5])
hold on
plot([0 1], [0, m1])
hold off
grid
axis([-0.1  1    -0.1  1.5])
axis equal
text(0.35, 1, sprintf('\\leftarrow \\theta = %.2f\\circ \\rightarrow', thd), 'Rotation',-thd, 'HorizontalAlignment','center')